I have a set time for every Tuesday. I wouldn't be able to go at various times each week but I certainly am flexible enough to allow for changes when things come up for either one of us. My therapist has a new policy where if you cancel a session you still have to pay for it.. no matter what. Fortunately since I've been with her for almost four years this doesn't apply to me, guess I was grandfathered in. But if it did apply to me I wouldn't like it. I can see if someone habitually cancels sessions or is always trying to change the time, then yes.. inconsistencies drive me crazy but let's say someone is in a wreck or has strep throat.. I don't think it is fair to make them pay for a session missed that they had no control over.